Testing of two communication processors generally requires the availability of device to monitor the flow of information between the processors. In many cases, during the development of a system of two communication processors, one processor will be completed before the other processor is. In order to assure proper behavior of the completed processor, test equipment is used to transmit test signals to the completed processor. In addition, test equipment also monitors signals generated by the completed processor. The monitored signals are compared to expected output from the completed processor. If unexpected output appears, the completed processor generally must be modified.
Communication systems, are combinations of several interconnected communication processors. Many processors are duplicates of each other, in that one communication processor performs the same function in the system as another. However, there are also many classes of processors. Each separate class of processor is intended to behave differently from other classes of processors. In many cases, each class of processor communicates according to one or more signaling protocols. Also, each class of processors must be tested and debugged. In addition, during the course of communication system development, a subsystem of processors must be tested. A subsystem is an interconnected set of processors of differing classes. These processors may be operatively connected through a wireline, radio link, fiber optic or any other electromagnetic coupling. A subsystem is different than a system in that a subsystem consists of a partial set of the processors required for a fully functional communication system.
The validation of a communication system can become very complicated because of the variety of processors and signaling protocols used to communicate amongst them. For example, consider a system composed of four processors of differing classes: A-B-C-D, where each processor is represented by the letters A,B, C and D, and interconnects are represented by `-`. The available subsystem configurations are:
______________________________________ A A-B B-C C-D B A-B-C B-C-D D ______________________________________
The task of testing is further complicated when multiple processors of the same class are built into a subsystem under test. A piece of test equipment must be able to communicate to each processor in the signaling protocol of the processor. The test equipment accomplishes the communication by transmitting a test signal to a processor in such a way that the test signal is recognizable as a valid signal of the signaling protocol used by the processor. In addition, the test equipment must be able to address the processor under test, in that the test equipment and subsystem under test must have an interconnection and that each device has the network address of the other device.
Each subsystem is responsive to one or more sets of test signals transmitted to and received from a plurality of network addresses. A test procedure consists of transmitting one or more test signals to the network addresses of the subsystem and receiving one or more response signals from the network addresses. A test signal is a digital packet made up of alternating high and low voltages, frequency shifts or whatever may be interpreted as a binary `1` or `0`. Usually a sequence of binary `1`s and `0`s, also known as bits, contains sequences which identify, among other things: the beginning of a packet; the end of a packet; the address to which the packet should be routed; parity, checksum and other error detecting sequences; a command and information required by a calling processor.
The nature and relative sizes of each sequence vary according to the application of the communication processor, thus a variety of protocols have been developed to serve the needs of each application--and new protocols are developed regularly for special purposes.
Conventional testing is accomplished by a single piece of test equipment, known as an interface device, which tests a developed processor by transmitting and receiving packets using the protocol to which the developed processor is responsive. The transmitting and receiving occurs under the programmed control of the interface device. The programmed control consists of a series of commands that build packets in the protocol being used, typically each sequence of bits must be specified by a separate command, which results in many lines of programming to define a packet and transmit a packet.
In many cases though, the developed processor is transmitting at multiple interfaces, often with multiple protocols. Therefore, a need exists for a way to gather commands into a single file which creates sections where code is translated by rules tailored to transmit and receive data content without having to explicitly specify the data format.